Recently, in semiconductor production apparatuses in which plasma steps are carried out, electrostatic chuck devices capable of easily mounting and fixing wafers on and to a sample platform and capable of maintaining the wafers at desired temperatures have been used. These electrostatic chuck devices include, in the upper portion, a ring member which surrounds a wafer-loading surface and is disposed at an outer circumferential edge portion of a wafer adsorption portion (focus ring).
In a state in which a wafer is placed in an electrostatic chuck device, the focus ring is disposed so as to surround the outer circumference of the wafer in a plan view. Therefore, when a forming material of the focus ring is selected, in the circumferential edge portion of the wafer, it is possible to form an electrical environment for plasma which is substantially the same as that in the wafer, and it is possible to prevent differences or bias of plasma treatments from being easily caused between the central portion and the circumferential edge portion of the wafer. For focus rings of the related art, as forming materials having a similar electrical conductivity to those of wafers which are process subjects, the same substance as wafers are frequently used. For example, in electrostatic chuck devices for processing silicon wafers, silicon focus rings are used.
However, when silicon wafers are processed in plasma steps in which chlorine-based plasma is used, silicon focus rings as described above are consumed at the same time. As a result, high frequency permeability near focus rings changes or thermal conduction properties change. Furthermore, there has been a problem in that, due to changes in the shapes of focus rings caused by heat and consumption, changes in the thermal conductivities of focus rings and focus ring-loading surfaces cause temperature changes of focus rings, and the treatment conditions of plasma steps become unstable.
Therefore, in recent years, focus rings made of silicon carbide which is a forming material that is not easily consumed by plasma have been proposed (for example, refer to Patent Literature No. 1).